— Worried about your kids watching the wrong stuff on TV? Don't trust the official suitability ratings either? An inventor in Salt Lake City, Utah, thinks he has the answer.

A computer connected to a TV set or Personal Video Recorder (PVR) simply monitors electronic programme guides along with the closed captioning text that accompanies programmes for hard of hearing viewers. Software then searches for dubious key words and the computer decides  based on the user's preferences  whether to block the entire programme or simply mute the sound for a short while.

Inventor Matthew Jarman gives some examples. If the programme uses the words "serial killer", the system could block a programme altogether. The same could go for anything that promises an appearance by Pamela Anderson.

The word "damn" could be acceptable on the Discovery Channel, but muted on all movie channels. And the word "bitch" might only be permitted during a programme about pets, and never if preceded by "you". Of course, parents could override everything with a password.

Checking tires for tread wear is a dirty job, and not easy to do accurately. But drivers need to know when a tyre tread has worn down to 3 millimetres or less, at which point road holding starts to suffer. IBM has a neat way for a car to monitor itself and display a warning on the dashboard when its tyres need changing.

Passive RFID tags are moulded into the tire tread, or stuck into the grooves. While the tags are still in place they reply to a trigger signal continually beamed from an antenna mounted beneath the car. But, as the tread wears out some of the tags are shed and stop responding. So the car automatically "knows" when its tires are getting dangerously thin.

A vehicle could also tell which tire is needs changing because the radio antenna is mounted off centre and thus at unequal distances from all four wheels. So the reply signals received from each tyre has a slightly different delay. The same system could work with trucks and aircraft tires too, IBM says.

Heres an idea for anyone who's felt sick after eating greasy fried food. Honeywell, based in New Jersey, US, has come up with an acoustic wave sensor that fits inside a deep fryer and constantly monitors the quality of cooking oil.

Fatty acids build up as oil is used in a fryer and eventually becomes deposited on food cooked in this way. Ultimately, this can cause indigestion for those who eat deep fried foods, Honeywell warns. Its acoustic sensor could detect this build up and warn a chef that the oil needs changing.

The system consists of an antenna that generates acoustic waves and a transducer made from a piezoelectric component, which picks up the acoustic wave and converts it into an electrical signal. The sensor is coated with material that reacts with fatty acids.

The acoustic waveform is damped and modified as fatty acids attach. A connected computer analyses this waveform signal and issues a warning to change the oil when it builds up too much.

For more than 30 years, Barry Fox has trawled through the world's weird and wonderful patent applications, uncovering the most exciting, bizarre or even terrifying new ideas. Read previous Invention columns, including: